title: Effects of dietary arginine on endocrine growth factors of channel catfish, Ictalurus punctatus.
abstract: Thyroid (TH) and growth (GH) hormones, and insulin-like growth factor I (IGF-I) are anabolic regulators in fish and responsive to nutrient intake. A study was conducted to determine if previously reported growth effects of dietary arginine (ARG) in channel catfish were related to the activation of endocrine axes. In a first experiment, catfish were fed incremental levels of ARG (0.5 - 4% of diet) for 6 weeks and sampled at 2-week intervals. In a second experiment, fasted (48h) fish were fed a single ration of ARG (0.5 or 4% of diet) and sampled at various intervals (0 to 72h postprandial, PP). Experiment 1 did not reveal any influence of ARG on circulating TH, GH, or IGF-I despite the significantly increased growth of fish fed ARG-enriched diets. In experiment 2, feeding the 4% ARG diet significantly increased the amplitude of pulsatile plasma GH levels and also significantly increased IGF-I mRNA in liver and muscle, (at 2h PP) and plasma IGF-I levels (at 6h PP). Although relatively infrequent sampling failed to reveal alterations in TH or GH levels in response to ARG-induced growth activation, PP high frequency sampling unveiled high amplitude pulsatile GH secretions and may be important in activating IGF production in target tissues. Additionally, expressed and secreted IGF-I exhibited discernible patterns which closely correlate with ARG-induced growth effects in catfish.
authors.affiliation: Department of Wildlife and Fisheries Sciences and Intercollegiate Faculty of Nutrition, Texas A&M University, College Station, TX 77840, USA.
authors.forename: Camilo
authors.initials: C
authors.lastname: Pohlenz
authors.forename: Alejandro
authors.initials: A
authors.lastname: Buentello
authors.forename: Thomas
authors.initials: T
authors.lastname: Miller
authors.forename: Brian C
authors.initials: BC
authors.lastname: Small
authors.forename: Duncan S
authors.initials: DS
authors.lastname: MacKenzie
authors.forename: Delbert M
authors.initials: DM
authors.lastname: Gatlin
mesh_terms: D000818:Animals; D001120:Arginine / Q000008:administration & dosage*; D004032:Diet; D019587:Dietary Supplements; D029941:Fish Proteins / Q000097:blood*; D005398:Fisheries; D007059:Ictaluridae / Q000097:blood / Q000254:growth & development*; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood; D013002:Somatomedins / Q000378:metabolism*; D013963:Thyroid Hormones / Q000097:blood*; D015430:Weight Gain
chemical_list: D029941:Fish Proteins; D036341:Intercellular Signaling Peptides and Proteins; D013002:Somatomedins; D013963:Thyroid Hormones; D001120:Arginine
keywords: Arginine; Channel catfish; Growth hormone; IGF-I; Thyroxine; Triiodothyronine